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Case Reports

Abstract

Monoclonal immunoglobulin deposition disease is an uncommon condition typically associated with plasma cell dyscrasias and rarely with B-cell neoplasms, the latter often in the context of IgM macroglobulinemia. We report the case of a 46-year-old female with a history of low-grade IgG lymphoplasmacytic lymphoma and severe seronegative inflammatory arthritis, who was admitted with new onset heart failure in the setting of multi-valvular stenosis. She was noted to have multiple pink nodules on the bilateral feet and ears, as well as numerous small firm papules over the face and thighs which had been present for 5 years. Multiple skin biopsies were obtained, all of which showed a pauci-cellular dermal nodule composed of eosinophilic material with PAS positivity. Congo red staining was negative for amyloid. The nodules demonstrated immunohistochemical positivity for IgG and kappa light chains, which was confirmed with direct immunofluorescence staining. Tandem mass spectrometry identified that immunoglobulin kappa light chain and a dominant heavy chain of IgG1 were both significantly enriched in lesional tissue. Electron microscopy revealed nodular dermal deposits of amorphous material with prominent formation of microtubular structures. Overall, findings were most consistent with light and heavy chain immunoglobulin deposition disease in the setting of a low-grade B-cell neoplasm. Given the patient’s constellation of symptoms and histopathologic findings in the skin, we suspect immunoglobulin deposition disease to be the cause of her valvular heart disease and erosive arthritis. To our knowledge, this is the first reported case of cutaneous immunoglobulin deposition disease in the setting of IgG lymphoplasmacytic lymphoma.